The present invention relates to an electrostatic copying apparatus utilizing a liquid developer and comprising means for automatically maintaining the copying image density constant.
A liquid developer used for electrostatic copying comprises a liquid carrier or dispersant and toner particles dispersed in the carrier. Only the toner particles are consumed in the developing process. Additional toner is supplied into the developer to compensate for the toner consumed in the developing process.
Various means have been proposed to maintain the copying image density constant such as sensing the toner density and maintaining the same constant. However, such an arrangement results in progressively decreasing copying image density due to fatigue of the toner and contamination of the carrier occuring over a period of time.